This study involves examining the sleep architecture (polysomnography) of patients with panic disorder, social phobia, and depression, in comparison with that of normal controls. Continued analysis of such factors as movement time, REM latency, wakefulness after sleep onset, and sleep efficiency among the groups is in progress. Sleep panic attacks have been studied specifically in that portion of panic disorder patients who have had these, and been found to arise from non-REM sleep -- either stage 2 or 3. On the nights when patients have had panic attacks, a prolonged REM latency has been noted, in contrast to the shortened REM latency of depression. End-tidal C02 is being measured and measures of sleep apnea and nocturnal myoclonus are being employed. New methods of data analysis of sleep records are being developed such as recording number of K-complexes, spindles, and performing spectral analysis of data for between group comparisons.